The invention relates to a locking device.
A locking device, such as shown in FIG. 7 of U.S. Pat. No. 2,806,723, has the disadvantage that it can only be located concentrically with respect to a rod or shaft that is to be locked. For this reason, essentially so-called locking cartridges have been developed that extend essentially perpendicularly to the rod or shaft to be locked. See, for example, German Patent Publication DE-A-40 12 524. Such known embodiments, however, have the disadvantage that they do not have a compact design, which limits their use.
The goal of the present invention is to provide a locking device with a compact design.
According to the invention, a locking device is provided in which two actuating jaws are mounted on a tilt bearing and have a through opening, with the distance from the midpoint of each through opening to the tilt bearing (first distance) and the distance from the midpoint of each through opening to the area of engagement of an actuating nose on each clamping jaw (second distance) being made so that the second distance is less than the first distance. A spring ensures that each clamping jaw abuts the surface of the rod to be locked in the vicinity of its through opening. This application force does not cause any clamping of the rod with the clamping jaw in this first position. It is only when a longitudinal movement of the rod is added that a self-clamping action is produced as a result of the considerable distance of the midpoint of the through opening from the tilt bearing on the one of the two clamping jaws which is located forward in the direction of movement of the rod. The clamping jaw located at the rear in the direction of movement of the rod does not lock and, even with the existing play of the locking cartridge, can abut the housing so that its clamping is released. The clamping jaw which is forward in the direction of movement, however, is moved away from the housing and can therefore not produce an undesired, premature release of the clamping. The spring must apply only enough force that the two clamping jaws are moved toward one another and abut the surface of the rod in the area of the through opening. The two clamping jaws in this position must of course have sufficient play by being spaced from one another in order to be able to exert a sufficiently reliable clamping action when the rod moves. Because no large springs and no large actuating levers are required, the locking device according to the invention can likewise have a compact design.
According to the invention, the actuating nose with its rear surface facing a supporting plane abuts the supporting plane of the actuating piston loosely, almost floating. As a result, the actuating piston can have a limited height without there being a danger that it will tilt when actuated, which would adversely affect the functional ability. Without the action of the actuating nose on the clamping jaws, the latter would be compressed by the force of the spring so that the clamping jaws in the first (unloaded) state would move toward one another around the tilt bearing. The through openings in the two clamping jaws, which grip the rod with limited play, in this first position produced by the force of the springs alone, clamp the rod. If the actuating piston is pneumatically actuated for example, the actuating nose is pushed between the clamping jaws and moved from the first-mentioned state, in which it is compressed by the force of the springs, into the second position, preferably into a parallel position of the two clamping jaws, so that the rod clamped by the limits of the through openings of the clamping jaws comes free and can be moved freely in this second position. This produces a short stroke to move the two clamping jaws into the second position.
The spring can be designed as an open, for example a toroidal, broken steel ring, or closed and for example can also be made of plastic. In the closed form, it can also be toroidal or a hollow cylinder. In the former case, it should be inserted into a circumferential groove that fits the shape of the spring. In the second case, with the plastic spring in the form of a hollow cylinder, assurance need only be provided that it can slip into its position, in other words as a result of impacts applied to its upper and/or lower sides. The spring can be located on the side facing away from the tilt bearing relative to the through openings of the clamping jaws and/or on the same side as the tilt bearing. The tilt bearing can be located as a point of contact of the two clamping jaws with one another and/or located in this area within the sleeve of the locking cartridge, or it can be a pin engaged separately in one end of the sleeve of the locking cartridge, along whose jacket the clamping jaws can move.
As a result of this design, without any fear of tilting the actuating piston, the latter can be made relatively short. Because of an actuating nose designed as a pin divided along the lengthwise axis, further shortening of the height is possible with this pin resting by its jacket on two correspondingly beveled guide surfaces of the clamping jaws and engaging them to displace the two of them from the first into the second position with minimal travel. This design permits an extremely limited height of the locking cartridge according to the invention.
By dividing each individual clamping jaw, at least two additional inner clamping jaws are provided whereby improved clamping function can be achieved without additional space being required. This advantageous improvement on the invention without considerable technical expense can be integrated into existing functioning systems, since only one part with no changes in the dimensions of the locking device, namely the two clamping jaws, must be replaced by the divided clamping jaws with one inner camping jaw each.
Especially advantageously, the locking device according to the invention can be used in a compact cylinder whose housing for this purpose has a preferably transverse cylindrical recess, preferably at right angles to the path of the rod to be locked.